SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
MITSUBISHI MICROCOMPUTERS
7560 Group
28
SERIAL I/O
Serial I/O1
Serial I/O1 can be used as either clock synchronous or asynchro-
nous (UART) serial I/O. A dedicated timer (baud rate generator) is
also provided for baud rate generation.
(1) Clock Synchronous Serial I/O Mode
Clock synchronous serial I/O mode can be selected by setting the
mode selection bit of the serial I/O1 control register to
“
1
”
.
For clock synchronous serial I/O1, the transmitter and the receiver
must use the same clock. If an internal clock is used, transfer is
started by a write signal to the TB/RB (address 0018
16
).
Fig. 23 Block diagram of clock synchronous serial I/O1
Fig. 24 Operation of clock synchronous serial I/O1 function
P
4
6
/
S
C
L
K
1
P4
7
/S
RDY1
P
4
4
/
R
X
D
P
4
5
/
T
X
D
X
I
N
1/4
1
/
4
F/F
Serial I/O1 status register
S
e
r
i
a
l
I
/
O
1
c
o
n
t
r
o
l
r
e
g
i
s
t
e
r
Receive buffer register
Address 0018
16
R
e
c
e
i
v
e
s
h
i
f
t
r
e
g
h
i
s
t
e
r
Receive buffer full flag (RBF)
R
e
c
e
i
v
e
i
n
t
e
r
r
u
p
t
r
e
q
u
e
s
t
(
R
I
)
Clock control circuit
S
i
f
t
c
l
o
c
k
S
F
c
l
r
r
c
i
a
k
l
s
e
I
/
e
n
O
l
c
1
c
y
s
t
i
d
y
o
i
n
n
v
c
i
s
h
i
i
o
r
t
o
n
n
i
z
a
t
i
o
n
o
e
e
b
q
u
r
a
t
i
o
1
/
(
n
+
1
)
Baud rate generator
A
d
d
r
e
s
s
0
0
1
C
1
6
BRG count source selection bit
C
l
o
c
k
c
o
n
t
r
o
l
c
i
r
c
u
i
t
Falling-edge detector
D
a
t
a
b
u
s
A
d
d
r
e
s
s
0
0
1
8
1
6
Shift clock
Transmit shift register shift completion flag (TSC)
Transmit interrupt source selection bit
Transmit buffer empty flag (TBE)
Address 0019
16
T
r
a
n
s
m
i
t
i
n
t
e
r
r
u
p
t
r
e
q
u
e
s
t
(
T
I
)
D
a
t
a
b
u
s
A
d
d
r
e
s
s
0
0
1
A
1
6
Transmit buffer register (TB)
Transmit shift register
R
e
c
e
i
v
e
e
n
a
b
l
e
s
i
g
n
a
l
S
R
D
Y
1
D
7
D
0
D
1
D
2
D
3
D
4
D
5
D
6
RBF = 1
TSC = 1
e
r
r
u
n
t
e
c
t
i
o
TBE = 0
T
T
B
S
E
C
=
=
1
0
Transfer shift clock
(1/2 to 1/2048 of the internal
clock, or an external clock)
e
r
S
i
a
l
o
u
t
p
u
t
T
X
D
S
e
r
i
a
l
i
n
p
u
t
R
X
D
Write signal to receive/transmit
buffer register (address 0018
16
)
O
d
v
e
n
e
r
r
o
r
(
O
E
)
N
o
t
e
s 1
:
T
s
I
f
o
T
h
h
u
h
e
i
f
d
t
p
e
t
o
t
a
u
r
r
a
p
c
e
c
n
e
i
s
s
r
n
e
m
a
w
t
i
v
i
i
t
o
i
t
n
i
n
e
u
i
n
t
h
n
o
t
e
e
a
u
r
r
r
s
o
l
r
u
u
t
y
p
e
h
f
p
t
d
e
r
o
t
(
(
T
e
t
r
m
R
I
d
a
I
)
)
c
(
n
t
h
i
a
n
S
m
e
s
s
b
e
=
b
g
)
f
p
h
e
,
f
e
i
n
e
n
b
r
.
n
e
y
r
t
r
s
e
a
e
g
t
e
t
t
i
s
d
i
n
t
e
e
g
r
i
t
t
w
h
h
e
e
h
r
e
t
n
w
r
a
h
n
T
e
s
S
n
m
C
t
i
=
h
t
0
e
i
n
,
t
t
t
r
e
h
a
r
e
n
r
s
p
t
r
m
t
a
i
s
s
t
o
m
b
u
f
c
t
f
e
e
c
r
l
s
o
r
e
e
c
g
l
e
k
i
c
i
s
s
t
e
i
o
g
r
n
e
h
n
a
b
e
s
t
r
a
(
e
T
t
e
m
I
C
d
p
t
o
i
o
e
d
f
n
h
i
n
(
T
e
u
B
s
o
E
e
u
r
=
i
a
l
y
1
l
a
)
I
/
n
o
O
d
r
1
a
s
f
t
o
r
e
n
i
a
r
t
l
t
r
h
o
d
e
l
a
r
t
t
e
a
r
a
g
i
n
i
s
s
s
t
m
e
i
.
t
t
t
r
i
e
n
t
n
T
s
C
i
t
1
u
u
n
u
r
i
t
i
)
c
t
c
e
r
2
:
a
t
s
t
s
t
o
T
X
D
e
t
3
:
w
h
e
r
e
c
e
i
v
e
b
u
f
f
e
r
f
u
l
l
f
l
a
g
(
R
B
F
)
b
e
c
o
m
e
s
“
1
”
.
D
7
D
0
D
1
D
2
D
3
D
4
D
5
D
6